A cable reel allowing electrical connection between a fixed housing and a movable housing has been used with a rotating mechanism such as the steering column of a motor vehicle. It is desirable to mount this cable reel on a steering column so that the movable housing can be rotated by the same force in both directions from the center position of the steering column. Prior art arrangements for correctly mounting the cable reel on the rotating mechanism use an index marking to correctly position the fixed housing and the movable housing. The position fitting mechanism of the prior art also provide a gear mounted on the movable housing which is engaged with a gear mounted on the fixed housing, such that the movable housing can only be rotated through a predetermined angle. The two gears comprise a locking member One gear of the locking member is mounted on the movable housing, while the other gear of the locking member is held to the fixed housing by a snap ring. After completing assembly of the entire rotating mechanism, the locking member can be separated from the cable reel (Japanese Laid-Open Publication No. 62-18355). The gear mounted on the fixed housing is equipped with a special tooth which can prevent rotation of the movable housing. Markings are provided for correctly positioning the two gears relative to each other. In this way the cable reel can be assembled on the rotating mechanism, such as a steering device, in its central position.
The locking member as described above is made of a hard substance such as plastic material, and thus after assembling the cable reel with the rotating mechanism, if the rotating mechanism is moved without the locking member being separated therefrom, it is impossible to rotate the movable housing past a certain point. At that time, if the movable housing is rotated by excessive force during checking after assembly, the components of the fixed housing engaged with the locking member may be broken and the broken pieces will inconveniently remain in the case, causing strange sounds during operation.
After the cable reel is assembled with the rotating mechanism, in light of the relationship between the cable reel and the other components assembled along with the cable reel, it may become necessary to remove the cable reel during maintenance, which is very inconvenient. The locking member must be replaced and the cable reel must be remounted. Thus, during remounting after replacing the locking member, even though the movable housing is correctly positioned relative to the fixed housing, it is possible for the movable housing to be displaced from its original position. Therefore, the cable reel and the rotating mechanism may be incorrectly assembled.